1. REFLECTIONS ON NANOTECHNOLOGY APPLIED TO DIELECTRICS IN A CONTEXT OF ELECTROTECHNICAL APPLICATIONS Presented by: Dr Michel Fréchette Senior researcher, Material sciences Institut de recherche d’Hydro-Québec (IREQ) Varennes, Québec, Canada, J3X 1S1 … invited talk given at the International Polyolefins Conference 2011 - Evolving Polyolefins Technology for the Global Economy. February 27 - March 2, 2011 at Hilton Houston North, Houston, Texas

2. Content I.What is a nanodielectric ? II.Current achievement with polymer nanocomposites III.Some near-future developments IV.Closing remarks 2/36

3. What is a nanodielectric ? Definition Fréchette et al., Conference on Electrical insulation and Dielectric Phenomena, 2001. 3/36

4. What is a nanodielectric ? TOLERANCE.. slight changes in one property.. large improvement or change.. still awaiting novelty We have been tolerant in regards of the results obtained 4/36

5. What is a nanodielectric ? NANOSTRUCTURE range ≤ 2 nm 5/36

6. What is a nanodielectric ? Advanced powder technology 6/36

7. What is a nanodielectric ? 7/36

8. PROCESS Energy due to combined attractive van der Waals and repulsive double layer forces at an interface. Dielectric Behavior of Silica-filled Epoxy Chen Zou et al., IEEE Transactions on Dielectric and Electrical Insulation, 2008 T.J. Lewis, Dielectrics Society meeting, 1997 8/36

9. Others Dimension of the stress Integration These are also elements playing an important role in the emergence of nanodielectric effects Some ND examples follow 9/36

10. Nanostructured microcomposite: Epoxy + micrometric quartz + nanoclay M. F. Fréchette et al., “Nanostructured Polymer Microcomposites : A Disctinct Class of Insulating Materials”, IEEE Trans. Diel. and Electr. Insul., 2008. 10/36

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14. IBM Research at Almaden 14/36

15. Fréchette and Reed, Conf. on Electrical Insulation and Dielectric Phenomena, 2006 15/36

16. Small quantity and no percolation Binding agents and sintering Advanced powder technology 16/36

17. PATTERNING IBM Research at Almaden 17/36

18. Current achievements WITH POLYMER NANOCOMPOSITES That is understood: inorganic nanofiller in a polymer matrix Imported for electrical insulation Focus on THERMOPLASTICs 18/36

19. Interface properties become increasingly dominant as the particle size is reduced. INTERFACE DOMINATED 19/36

20. State of understanding Polymer morphology Nucleation site, Cristallinity, Orientation Note : Amorphization induces more space charge Nanostructure + surface Surface reactivity ( surface to volume ratio) Functionalization Agglomeration Impurities (e.g. water) Local permittivity gradients 20/36

21. State of understanding Interphase Interaction zone (between nano/matrix) Free volume (packing, Charge, Different states) Viscosity gradient Building blocks (go with the concept) Variance: Impurities, Particle sizes and shapes, Defects (e.g. bubbles), etc. 21/36

22. The cumulative probability of breakdown (DC, uniform field) as a function of electrical field for crosslinked polyethylene containing different nanoparticles. TES=Triethoxyvinysilane, AEAPS – aminpropyl-trimethoxysilane, HMDS = hexamethyldisilazane. M. Roy et al., IEEE Trans. on Dielectrics and Electrical Insulation, 2005 22/36

23. Water tree growth for XLPE-SiO2 nanocomposite with loadings of: 0% (  ), 5% ( ), and 12.5% (  ). L. Hui et al., Conference on Electrical Insulation and Dielectric Phenomena, 2009 23/36

24. Sami et al., Conference on Electrical Insulation and Dielectric Phenomena, 2009 Weibull plots of dielectric breakdown strength of neat HDPE and HDPE with SiO 2 nanoparticles. 24/36

25. AC erosion depth vs. voltage application time for PNC with 0, 2 and 6 wt% C15A. N. Fuse et al., Conference on Electrical Insulation and Dielectric Phenomena, 2009. 25/36

26. Fréchette et al., International Conference on Solid Dielectrics, 2010 26/36

27. Castellon et al., Conference on Electrical Insulation and Dielectric Phenomena, 2010 27/36

28. Stress-strain characteristics of PVA with and without 0.8% wt% carbon nanotubes. L. Lui et al., Advanced Functional Materials, 2005 28/36

29. Outstanding features Partial nanostructuration of polymer nanocomposites were found: to change morphology and related properties to improve partial-discharge resistance, to suppress space charge formation and affect charge relaxation, and to prolong the treeing lifetime to open a way to tailoring/design 29/36

30. What is lacking ? The possibility to link (clearly and easily) the nano intervention to the macroscopic property To make the materials with reproducibility and with successful quality control To establish the stability and ageing of the nanocomposites 30/36

31. Such a case Nanoclay in PP A lot of information on nanoclay (1960s) Controled-preparation in the framework of VAMAS round-robins L. A. Utracki, Clay-containing polymeric nanocomposites and their properties, IEEE Electrical Insulation Magazine, 2010 Fréchette et al., Nanodielectrics: A Panacea for Solving All Electrical Insulation Problems ?, International Conference on Solid Dielectrics (ICSD), 2010 31/36

32. Many considerations Compatibilization Nucleation (Clay) vs comp./intercalant Crowding of platelets (less than 1%) Interlayer spacing, solidification (6 nm) Clay impurities /Catalysis / Ageing Intrinsic less / Comp. and inter. more 32/36

33. Breakdown strength vs. aging time for PNC with 0, 2 and 4 wt% synthetic organoclay. A. Bulinski et al., Conference on Electrical Insulation and Dielectric Phenomena, 2009 33/36

34. FUTURE Extra-ordinary additive or fillers (mastering) Tailoring 2 or more properties at the same time (multi-filler) Higher-degree self-assembly nanodielectrics (BB and B) 34/36

35. Closing remarks The question (1998-2001) 35/36

36. Closing remarks DESIGN 36/36 SPECIAL ACKNOWLEDGMENT for TP work at IREQ: Prof. E. David (ÉTS) and Ph.D. student A. Sami; and S. Savoie (IREQ)